Zein solution and coating composition



Patented 26, 1939 PA'rsi ZEIN SOLUTION AND comma COMPOSITION Roy E. Coleman, Chicago, 111., assignor to The Zein Corporation of America, a corporation of Delaware No Drawing.

18 Claims.

This invention relates to improvements in substantially anhydrous solutions and coating compositions of zein and to methods of preparing the same. While the present invention is applicable to the production of solutions and coat ing compositions of other prolamins, it is particularly directed to securing substantially anhydrous solutions and coating compositions of zein with controlled solution and gelling characteristics, zein being differentiated from other prolamins by its unusual gelling tendencies.

This application is a continuation-in-part of my prior copending applications Serial No.

- 153,210, filed August 9, 1937; Serial No. 158,215, filed August 9, 1937; and Serial No. 158,737, filed August 12, 1937.

The solutions and coating compositions of my present invention are characterized by the fact that they contain either no added water or only very slight amounts of water not in excess of about 5% and are, therefore, substantially anhydrous.

The zein used in accordance with my invention may be the commercial zein which contains a small percentage of moisture in the order of about 5 to about 8%, preferably about 8%, and

is obtained in the trade in powdered form, or it may be a specially treated substantially anhydrous zein. In the following description oimy invention I refer by the term zein to commercial zein or to zein of substantially the water content of commercial zein unless otherwise specifically designated.

In the prior art zein coating compositions, water has been included to a substantial extent, it being considered that the solubility characteristics of zein required the inclusion of substantial proportions of water in organic solvents.

For example, as stated in the Walsh et a1. Patent No. 1,966,604, the addition of water is necessary since the low molecular weight alcohols, alcoholethers and alcohol'derivatives are not effective alone in making solutions of zein.

In accordance with the present invention I what below. When cooled even to temperatures Application September 21, 1989, Serial No. 295,919

as low as 10 above zero or to zero, solutions or coatings prepared in accordance with the present invention may separate and become solid; however, on heating again to temperatures of from about 45 to F., a re-solution is effected, either without stirring or with slight stirring, and the solutions and coatings return to their normal form at the re-heating temperatures.

The stable non-separating solutions and coating compositions prepared in accordance with the present invention may be controlled as to their gelling characteristics, as hereinafter set forth, and may be slow gelling or substantially nongelling with slight tendency to increase in viscosity; that is, to thicken or become heavier in body; and in many instances they exhibit practically no tendency to thicken or to gel overpractical periods of time in the order of about 3 to about 6 months. By virtue of these novel stable characteristics, the solutions and coatings of my invention are not limited to use immediately or within short periods of time after preparation as is generally the case with the prior art solutions and coating compositions. The solu-. tions and coating compositions of the present invention generally remain stable and reasonably constant in their characteristics during the periods necessary for transportation and distribution, either in bulk or in packages, or for storage for reasonable periods of time, and hence their field of applicability is greatly increased.

In accordance with the present invention, I havefound that solutions and coatings of zein having the desired non-separating, controlled gelling or non-gelling characteristics may-be secured by a suitable balance between the hydrocarbon constituents or radicals present in the solvent or solvent mixtures and the polar constituents, or radicals present therein, the presence of a certain proportion of carbon-bonded hydroxyl radicals being required to secure solvent action. The presence of a hydroxyl group in a primary alcohol radical, CI-IzOH, appears to be particularly helpful in securing such action. The presence of an excessive proportion of hydroxyl radicals or of polar radicals including some hydroxyl radicals causes or accelerates gelling tendencies in the zein solution or coating. Polar radicals such as O- (ether oxygen), Cl, --NH2, =CO and COOH thus appearto aid or cooperate with OH in securing the necessary conditions of polarity in the solvent (in which term I include solvent mixtures in'the present case) for solvent action, and in excess produce the conditions enhancing gelling.

' is possible, by simple experimentation, to deter- While in solutions absence of gelling or slow gelling'or thickening is desirable, in the preparation of plastics rapid gelling may be desirable. In the present case I am more particularly concerned with solutions having slow gelling or substantially non-gelling characteristics for use in coating compositions: i. e. solutions which do not gel or which gel or thicken so slowly as to permit normal commercial handling without material or serious thickeningor gelling.

The proportion of hydrocarbon or non-polar radicals in the solvent or solvent mixture should not be excessive, since too high a proportion of hydrocarbon apparently causes insolubility and separation of the zein. The same is the case in the presence of excessively long or large hydrocarbon radicals; -e. g. C4 and higher alkyl radicals. Cyclic hydrocarbon radicals, however, behave as lower alkyl radicals. Thus, as will appear hereinafter, the benzyl radical acts as if it were intermediate between the methyl and ethyl radicals. This is consistent with the polar characteri'stics of aryl-alkyl radicals as compared with alkyl-alkyl radicals.

$5 The desired balance of polar'constituent radicals and hydrocarbon or non-polar radicals in the solvent may be secured by the use of a suitable individual compound which inherently has the necessary balance, or by an admixture of compounds which are individually not balanced to secure proper relations in the mixture and which individually may not be solvents for zein. The behavior of such mixtures may be explained by assuming s'olvation of the zein molecules or 35 miscelles by the hydroxylated constituents of the mixture, with orientation of the hydrocarbon radicals of the hydroxylated compound to the exterior of the solvate complex, which may then disperse or dissolve in the remaining constituents of the solvent.

The proportion of polar radicals to hydrocarbon or non-polar radicals which I have found to be desirable lies within a range which extends between the limits of absolute methanol on the one hand, having 53% hydroxyl and 47% hydrocarbon, and absolute ethanol on the other hand having 37% hydroxyl and 63% hydrocarbon. This range is approximate and may vary somewhat depending on the solvent or solvent mixture used. The limits of this range are, however. indicative of gelling characteristics on the one hand and of insolubility on the other and. therefore, provides a close and adequate guide to enable the operator. by simple experimentation. to determine the required balance of polar and hydrocarbon radicals to eii'ect solution of zein in any solvent or mixture of solvents of a character herein. set forth. Thus absolute methanol has decided solvent action, but has excessive gellin tendencies, as has also ethylene lyco which has an even higher proportion of -OH than has methanol. methanol. shows n a preciab e solvent action on zein. a behavior which is probably related to its 65 high surface tension. On the other hand. abso- I lute ethanol. isopro anol. and hi her alcohols have no a parent solvent action.

It is. of course. obvious that certain solvents 70 or mixtures of solvents havin a balance of polar set forth will produce solutions or coatings-which are more suitable for special commercial purposes than other balanced solvents orbalanced 75 mixtures of solvents. By using the critical polarhydrocarbon radical balance range as a w de, it

Glycerol. also hip-her in QH t and hydrocarbon radicals within the limits above mine readily that particular balanced solvent or balanced mixture of solvents which will produce the solution or coating composition having the desired properties and characteristics for the Q special purpose. 7

Various relatively high molecular weight 'alcohols, having a ratio of polar to non-polar radicals between methanol and ethanol are excellent individual solvents for zein with the production 0 of non-gelling, non-separating solutions and coatings, as set forth in my prior applications Serial No. 187,559, Serial No. 187,560, and Serial No. 188,182, which were filed as continuations-inpart of application Serial No. l58.2l5. 15

In the following examples, I illustrate such solvents as well as the methods for producing coating compositions in accordance with my invention. The'solutions produced in accordance with the methods-set forth in the ,following examples are stable against separation ,and are controlled to be slow gelling or substantially nongelling over practical periods of time; in many cases over from about 3 to about 6 months. In the following examples and in all other examples in this application, the term parts indicates parts by weight.

Example 1 10 parts of zein are mixed with parts of di- 30 ethylene glycol in a suitable vessel. On stirring I the mixture at room temperature the zein is converted into a viscous, translucent, semi-plastic mass. On the application of heat in the order of about 150 F. and with continued stirring, a 'clear, non-separating,

non-gelling, stable solution of zein in the diethylene glycol is obtained in about 5 to 10 minutes.

Example 2 i 10 parts of zein are mixed with 40 parts of triethylene glycol. On stirring and with the application of heat in the order of 140 to 150 F., a clear, non-separating, non-gelling stable solution of the zein in the solvent is obtained in about 6 5 solution of the zein in the solvent is obtained in about 3 to 10 minutes.

Example 4 I 10 parts of zein are mixed with 40 parts of diacetone alcohol in a suitable vessel. On standing and with the application of heat in the order of to F., the zein becomes plastic and 60 separates from the solvent. At these temperatures the zein does not appear to dissolve in the solvent. On continued stirring and with the application of heat in the order of F the zein forms a gelatinous mass. On further stirrin g5 and on the application of heat in the order of to 200 F. a colloidal solution is formed which is slightly cloudy. This colloidal solution is formed in about 10 to 15 minutes. On cooling and standing, the solution becomes quite viscous, 70 but turns clear and remains stable. Very small proportions of water, say 1 to 3%, or of methanol or glycol may be incorporated insolutione containing diacetone alcohol, reducing their viscosity.

' benzyl alcohol in a suitable vessel.

Example 5 10 parts of zein are mixed with 30 parts of On stirring and with the application of a slight heat in the order of about 115 to 120 F., a clear, brilliant, non-separating, non-gelling stable solution of the zein in the benzyl alcohol is obtained in about 5 to 15 minutes. The solution is rather viscous.

' Example 6 10 parts of zein are mixed with 50 parts of Example 7 10 parts of zein are mixed with 40 parts of cyclohexanol (containing 2% by weight of water) in a suitable vessel. On stirring and with the application of heat in the order of about 170 to 180 F., a non-separating, substantially nongelling stable solution of the zein in the cyclohexanol is obtained in about 7 to 12 minutes.

The solution is quite viscous, and as in the case of diacetone alcohol, small proportions of water, methanol or glycol reduce the viscosity of the solution.

Example 8 10 parts of zein are mixed with 40 parts of furfuryl alcohol in a suitable vessel. On stirring and with the application of heat in the order I of about 185 to 195 F., a clear, non-separating,

non-gelling stable solution of the zein in the furfuryl alcohol is formed in about 5 to 10 minutes. 1

Tetrahydrofurfuryl alcohol, a balanced solvent, may be used in lieu of the balanced solvents of the above examples.

Considering the cyclic and aryl-alkyl radicals of the group of compounds set forth in Examples 5 to 8 inclusive as intermediate between the CH3 and the CH3CH2 radicals, it will be noted that in all of these solvents the proportion of polar radicals (--OH or -OH and -O-) may be regarded as if it were intermediate between the ratios for methanol and ethanol. I have found that any of the above balanced solvents or mixtures of them may be used in or added to other solvents or solvent mixtures, otherwise balanced or approximately balanced, such additions being frequently desirable. Thus, benzyl alcohol aids in securing a bright clear zein film. In general, also, these solvents may be used with various proportions of ethanol, glycol or the like, providing the ratio of hydroxyl and other polar groups to hydrocarbon radicals is maintained within the proper balance, as set forth in the following examples.

In the followingexamples, when I refer to anhydrous denatured alcohol I have reference to the, commercial anhydrous denatured alcohol of the following formula:

- Per cent Anhydrous 'ethyl alcohol approximately 89.3 Anhydrous methyl alcohol do 4.4

Ethyl acetate; do. .63

" Example 9' 10 parts of zein are mixed with 40 parts of a solvent mixture containing 84% of 95% alcohol 8 to 12 minutes.

and 16% of diethylene glycol. The mixture is stirred and on the application of heat in the order of about to F. for about 5 minutes, a clear, non-separating, substantially non-gelling stable solution of the zein is formed.

Example 10 4 10 parts of zein are mixed with 20 parts of a solvent mixture containing 50% of benzyl alcohol and 50% of 95% alcohol. On stirring and with theapplicatiqn of heat in the order of about 108 to 112 F. a non-separating, substan-' tially non-gelling stable solution of the zein in the solvent mixture is obtained in about 5 to 8 minutes. i

Example 11 10 parts of zein are mixed with 20 parts of a solvent mixture containing 50% of benzyl alcohol and 50% of anhydrous denatured alcohol. On stirring and with the application of heat in the order of about 90 to F., a non-separating, substantially non-gelling stable solution of the zein in the solvent mixture is obtained in about 5 to 8 minutes.

Example 12 10 parts of zein are mixed with 35 parts of a solvent mixture'containing 22.2% of diethylene glycol monomethyl ether and 77.8% of cyclohexanol. On stirring and with the application of heat in the order of about 165 to. 170 F., a stable, slow-gelling solution is obtained in about Example 13 10 parts of zein are mixed with 25 parts of diethylene glycol monoethyl ether and-15 parts of propylene glycol in a suitable vessel. On stir ring and with 'the application of heat in the order of about to F., a stable, slow gelling solution is obtained in about 5 to 10 minutes.

Example 14 Example 15 10 parts of zein are mixed with 20 parts of diethylene glycol monoethyl ether and 30 parts of diacetone alcohol in a suitable vessel. On stirring and with the application of heat in the order of about 135 to F., a stable, slow gelling solution is obtained in about 5 to 10 minutes.

Example 16 10 parts of zein are mixed with 20 parts of ens diethylene glycol monoethyl ether, 12 parts of triethylene glycol and 8 parts benzyl alcohol in a suitable vessel. On stirring and with the application of heat in the order of about 120 to 130 a stable, slow gelling solution is obtained in about 8 to 12 minutes.

Example 17 added. The resulting solution is non-separating and substantially non-gelling.

V V I Example 18 10 parts of zeinare mixed with 80 parts of a solvent mixture containing of diacetone alcohol and 50% of 95% alcohol. In practice, the zein is mixed with'the diacetone alcohol and heated to about 190 to 200 F. for about 8 to 12 minutes to effect solution; The solution is then cooled to about 130 to 140 F. and the 95% alcohol is then added. The resulting solution isnonseparating and substantially non-gelling.

' Example .19

10 parts of zein are mixed with 200 parts of a solvent mixture containing 40% of propylene glycol and to 95% alcohol. In practice, the zein is heated in the propylene glycol to about 165 to 170 F. to effect solution. The solution is then cooled to about 130 F. and the 95% alcohol is then added. The resulting solution is nonseparating and substantially non-gelling.

Example 20 v 10 parts of zein are mixed with 20 parts of ethylene glycol and 20 parts of diethylene glycol.

On stirring and with the application of heat in the order of about 185 to 195 F., a clear, nonseparating, substantially non-gelling stable solution of the zein in the solvent mixture is obtained in about 8 to 12 minutes.

Example 21 10 parts of zein are mixed with 30 parts of benzyl alcohol and 20 parts of ethylene glycol in a suitable vessel. On stirring and with the appliwith the application of heat in cation of heat in the order of about to F., a stable, slow gelling solution is obtained in about 5 to 10 minutes.

Example 22 10 parts of zein are mixed with '70 parts of propylene glycol and 30- parts of glycerine in a suitable vessel. On stirring and with the application of heat in the order of about 140 to F.,

a stable, slow gelling solution is obtained in about 8 to.12 minutes.

' v V Eaample 23 v w 10 parts of zein are mixed with 48 parts of diacetone alcohol and 12 parts of ethylene glycol in a suitable vessel. On stirring and with the application of heat in the order of about 160 to F. a stable, slow gelling solution is obtained in about-5 to 10 minutes.

Example 24 10 parts of zein are mixed with 32 parts of triethylene glycol and 8 parts of glycerine in a suitable vessel. On stirring and with the applica- 10 parts of zein are mixed with 10 parts of a. solvent mixture containing 50% of benzyl alcohol and 50% of furfurylalcohol. On stirring and g g the orderof 190 to 200 F., a' non-separating, substantially nongelling stable solution of the zein in the solvent mixture is obtained in about 10 to 15 minutes.

Example 26 10 parts of zein are mixed with so. parts b1 propylene glycol and 10 parts of .benzyl alcohol in a suitable vessel. On stirring and with the application of heat in the order of about 1'70 to 185 F.,

a non-separating, substantially non-gelling stable solution of the zein in the solvent-is obtained in about 10 to 15 minutes.

'- Example 27 10 parts of zein are mixed with 30 parts of cyclohexanol and 20 parts of triethylene glycol in a suitable vessel. On stirring and with the application of heat in the order of about 150 to 160 F., a non-separating, substantially non-gelling stable solution of the zein inthe solvent mixture is obtained in about 8- to 12 minutes.

Example 28 10 parts of zein are mixed with 10 parts of diacetone alcohol and 30 parts of diethylene glycol in a suitable vessel. On stirring and with the application of heat in the order of about '160 to F., a non-separating, substantially nongelling stable solution of the zein in the solvent mixtureis obtained in about 10 to l5-minutes.

Example 29 10 parts of zein are mixed with 30 parts of furiuryl alcohol and 20 parts of propylene glycol in a suitable vessel. On stirring and with the application of heat in the order of about 1'75 to F., a non-separating,- substantially non-gelling stable solution of the zein in the solvent mixture is obtained in about 5 to 10 minutes.

Solvent mixtures of non-gelling or controlled gelling characteristics may be produced by mixing miscible compounds having a deficiency of hydroxyl or polar radicals with compounds having a balance or an excess thereof to secure the desired balance of polar and hydrocarbon radicals in the resulting mixtures. An extreme ex-. ample of the production of such solvents is the admixture of toluene (a non-solvent for zein) and methanol. Mixtures of methanol and toluol containing'5 to 45% of toluol are excellent solvents for zein, and have retarded and in some cases relatively slow gelling tendencies. The preferred range is 35 to 45% toluol. The following examples are illustrative of such mixtures. By the expression retarded gelling tendencies as used in these examples and elsewhere throughout the specification, I mean solutions of zein in solvent mixtures which have retarded gelling tendencies with respect to the gelling time of solutions of zein in the constituent of the mixture of solvents having a tendency'to form a gelling zein solution.

Example 30 10 parts of zein are mixed with 40 parts of a mixture consisting of about 55% of methanol and about 45% of toluol. On stirring and with the application of heat in the order of about 100 -to-105 F., a non-separating, stable solution of the zein in the solvent mixture having greatly retarded gelling tendencies is obtained.

n Example 31 115 to 125 F., a non-separating, slow-gelling, stable solution of the zein in the solvent mixture is obtained.

- Example '32 Example 33 10 parts of zein are mixed with 18 parts of methanol and 22 parts of benzol inv a suitable vessel. On stirring and with the application of heat in the order of about 90 to 110 F., a nonseparating, stable solution of the zein in the solvent mixture having retarded gelling tendencies is obtained. Y

Ezcample 34 10 parts of zein are mixed with 125 parts of-a solvent mixture containing 40% of cyclohexanol, 40% of 95% alcohol, 10% of 'toluol, and 10% of linseed fatty acids. In practice, the zein is heated in the cyclohexanol to about 190 to 200 F., to eifect solution. .The solution is then cooled to about 130 F., and the other ingredients are added. The solution formed is stable and nongelling.

Anhydrous or substantially anhydrous solvents may be prepared from the aliphatic alcohols having from 2 to 4 carbon atoms by adding thereto hydroxylated or polar compounds having higher ratios of OH or polar groups (including CO, NH2, 0 or -OH) than ethanol to secure the desired balanced relations between polar and non-polar groups. The simplest monoand-polyhydric alcohols are particularly useful in this connection, these being methanol glycol and glycerol. The following examples are illustrative of zein solutions prepared with such solvent mixtures in accordance with my invention.

Example 35 10 parts of zein are mixed with 40 parts of a solvent mixture containing 86% of 95% alcohol and 14% of ethylene glycol. The mixture is stirred and onthe application of heat in the order of about 90 to 95 F., a clear, non-separating, slow-gelling, stable solution of the zein in the solvent mixture is formed.

Example 36 10 parts of zein are mixed with 40 parts of a solvent mixture containing 89% of 95% alcohol and 11% of dichlorethyl ether. On stirring and with the application of heat in the order of about 75 to 85 F., a non-separating, substantially slowgelling, stable solution of the zein in the solvent mixture is obtained.

Emample 37 10 parts of zein are mixed with 44 parts of 95% alcohol and 6 parts of dioxan in a suitable vessel. The mixture is stirred and on the application of heat in the order of 75 to 85"F.', a stable, nonseparating slow-gelling solution of the zein is produced.

Example 38 10 parts of zein are mixed with 30 parts of a solvent mixture containing 50% of ethylene glycol monomethyl ether and 50% of anhydrous denatured alcohol. On stirring and with the appli- -ent in solution in excess, that it tends to cause cation of heat in the order of to F., a stable, non-separating slow-gelling solution is obtained.

. Example 39 10 parts of zein are mixed with 40 parts of a 5 solvent mixture containing 84% anhydrous denatured alcohol and 16% of ethylene glycol. The mixture is stirred and on the application of heat in the order of about to F., a clear, nonseparating, slow-gelling, stable solution of zein in 10 the solvent mixture is obtained.

Example 40 10 parts of zein are mixed with 30 parts of anhydrous isopropyl alcohol and 20 parts of C. P. 15 glycerine in a suitable vessel. On stirring and with the application of heat in the order of about to 125 F., a non-separating, slow-gelling, stable solution of the zein in the solvent mixture is obtained.

. 80 Example 41 10 parts of zein are mixed with 25 parts of 95% isopropyl alcohol and 5 parts of ethylene glycol in a suitable vessel. On stirring and with the application of heat in the order of about 110 95 to F., a non-separating, slow-gelling, stable solution of the zein in the solvent mixture is obtained.

It is apparent that ethylene dichloride, tetrachlorethylene and the like may be used in lieu 30 of dichlorethyl ether in the above examples. It is also apparent, in accordance with the present invention, that the proportions of these materials used in admixture with the low-molecular weight alcohols must be controlled so that the 35 desired balanced relations between polar and non-polar groups are secured.

- The solvents and solvent mixtures for zein set forth above, as well as other solvents or solvent mixtures which will be apparent from the fore- 40 going, and the resulting solutions prepared in accordance with the present invention are substantially anhydrous, containing not more than 5% of added water and, preferably, susbtantially less. The proportions of water permissible are 45 thus limited in order to secure the desired solution characteristics and control of gelling, since excess of the proportions above indicated dis turbs the balance of the solvent, tending to produce or to accelerate gelling, as well as to impair the character of the zein film deposited from the solution. Possible explanations of the behavior of water may be made on the basis that it acts as a highly polar constituent when pressolvation or hydration of the zein, and its tendency to cause gelling may also be related to its high surface tension. The permissible proportion may vary in various solvents or solvent mix- 00 tures, the maximum permissible being represented by the permissible proportion of 5% in the case of ethyl alcohol or the ethyl alcohol constituent of the solvent. Since ethyl alcohol with 5% water is a solvent producing stable solution in 05 only limited cases, as set forth in my application Serial No. 158,215, and in all other instances is but one constituent of a mixture,.it-will be apparent that the solvents prepared in accordance with the present invention contain (except in 70 those specific instances) substantially less than 5% of added water.

The extent of the effect of water and the permissible proportion thereof varies with the solvent or solvent mixture and, in general, the more 7 the desired balance of polar groups and hydrocarbon constituents, the less the permissible proportion of water to avoid the introduction of ex-' cessive gelling or insolubility. In some cases small proportions of water below the limits above set forth may be advantageous, as in the case of Example 4, supra. The maximum permissible proportion may be readily. determined experimentally in each instance and in many cases may be as low as 2 or 3%.

By the term substantially anhydrous", in connection with solvents or solvent mixtures, as used herein, I means having insumcient water in the solvent or solvent mixture to disturb the balance thereof and introduce excessive gelling or insolubility, and having in no case more than 5% water.

By the use of anhydrous or substantially anhydrous solvents or solvent mixtures in accordance with myvinvention, I am thusenabled to prepare substantially non-aqueous zein solutions and coating compositions which contain no added water, or only slight amounts thereof, not in excess of 5% and, preferably, less. By virtue of this low added water content, the field of applicabilityof the coating compositions and solutions in accordance with my invention is materially widened beyond that of the aqueous coating compositions of the prior zein art. In addition, the films deposited from my coating compositions and solutions have none of the serious drawbacks. as to brittleness, lack of luster and gloss and blooming and blushing tendencies of the films deposited from the aqueous solutions or coating compositions of the prior art.

Certain anhydrous or substantially anhydrous compounds or mixtures of compounds in accordance with my invention, characterized in having a balance of polar and hydrocarbon radicals approaching that of ethanol and bordering the desired range, have been found to be excellent sol-. vents for zein. Solutions or coating compositions formed by the aid of these solvents are stable against separation of the zein and produce solutions in which the gelling tendencies can be more readily controlled than in the case of solutions or coating compositions formed by the aid of these solvents and substantial amounts of water as in the prior art. Of thesolvents, mention .may be made of ethylene glycol monomethyl ether, di-

ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, diethylene glycol monoethyl ether and. like alcohol-ether solvents or mixtures thereof. The following examples are illustrative of solutions prepared with these solvents.

V Eqrample 42 10 parts of zein are mixed with 40 parts 0 ethylene glycol monoethyl ether in a suitable vessel. on stirring the mixture at room temperature (about 73 F.) for about 3 to 4 minutes, the zein is converted into a viscous, translucent, semi-plastic mass. On continued stirring for about 1 to 6 minutes, a clear, bright, straw-colored, non-separating slow gelling,, stable solution of the zein in the solvent is obtained.

Example 43 10 parts of zein are mixed with 30 parts of diethylene glycol monomethyl ether. 0n stirring the mixtureat room temperature, it is found that the zein mixes readilyv with the solvent and forms a cloudy mixture containing considerable agglomerated particles but the solution of the zein is not readily afiected. Cn theapplication:

heat in. the order of about 150 F. and with con-z.

tinued stirring, a clear, non-separating, slow gelling, stable solution of the zein in the solvent is obtained in about 8 to 15 minutes.

Example 44 10 parts of zein are mixedwith 40 parts 0 ethylene glycol monoethyl ether; The mixturemixes well at roomtemperature but does 'not quickly dissolves On stirrin'g'for about 5 "min utes and with the application of heat in the order of to F. the zein begins to go into solution. On continued stirring for about 5m 10 minutes and with the further application of heat in the order of to F., a clear, bright, nonseparating, slow gelling, stable solution of the i more parts by weight of the solvent to 1 part byweight of the zein., In most instances, 3 to 5 7 parts by weight of the solvent to one part by weight of the zein has been found suflicientto dissolvethe zein and form the desired stable soand gelling tendencies of the-solutions orcoating compositions prepared. in accordance with 7 my invention are at least in part dependent on the.

proportion of solvent used.

The coating compositions embodying my in vention have the unusual properties, particularlutions or coating compositions. The viscosity ly when heated, of being able to give up their l solvent or solvents readily when applied to any-- surface to quickly and readily form tough, fiex ible, non-tacky, hard andgenerally transparent films even when'retaining .some solvent. The

films deposited from coating compositions in accordance with my invention are very strong-and have unusual adherent properties. In these coating compositions the film forming properties thereof can be built up to produce a filmof greater toughness, flexibility, hardness and gloss than is capable of being formed from coating compo sitions containing added water in an amount greater than 5% as in the prior art. Under normal temperature conditions, the solutions or coatmg compositions in accordance with my inventionwill produce non-blushing coatings on drying, without the aid of supplementary anti-blushing agents as in the prior art" The coating compositions in accordance with my invention may be applied to any surface and they may be-used for coating, sizing, or impregnating any material, such as. paper, textiles, wood,

wood pulp and the like. When coated on paper, Cellophane, glass and the like, a film is formed almost immediately .which possesses the film characteristics set forth above. Since these coating compositions have decided adhesive properties, they may be used either'per se or in combi nation with other materials for uniting or lamihating paper, cloth, wood, glass, felt, Cellophane,

metals and metal foils and the like. The characteristics of the coating compositions in accordance with my invention, and hence of the ultimate: films formed therefrom, can be altered at will and as desiredv by the inclusion of diluents, modifiers, plasticizers, fillers *and the like. Thus, the coating compositions may 'be modified by the inclusion therein of common lacquer solvents or lacquer plasticizers and the like such as, for example, dioxan; the ketones such as acetone, methyl ethyl ketone,'di-isobutyl ketone and the like; the esters such as methyl acetate, ethyl acetate, ethyl butyrate, butyl butyrate, glycol diacetate, the esters of the glycol ethers and the like; the alcohol ethers such as ethylene glycol monobutyl ether, diethylene glycol monobutyl ether and the like as well as glycerine derivatives; the alcohols such .as ethanol, denatured alcohol, butanol, isobutanol, amyl alcohol, and higher alcohols such as octyl alcohol, cetyl alcohol, lauryl alcohol, myristyl alcohol-and the like; the hydrocarbons such as benzene, toluene, xylene, cyclohexene and the like; chlorinated compounds such as ethylene dichloride, monochlorobenzene, orthodichlorobenzene, dichloroethyl ether and the like; furane derivatives such as furfuryl acetate, iurfural and the like; and plasticizing esters such as dimethyl phthalate, diethyl phthalate, dibutyl phthalate, tricresyl, and triphenyl phosphates and the like. It is obvious from the foregoing that other wellknown common lacquer solvents, lacquer plasticizers and the like may be used in lieu of those hereinabove set forth. 7

The characteristics such as. spread and flow of these coating compositions may also be modified by the addition of a fatty acid such as, for example, oleic, linseed, hemp seed, lauric and like fatty acids having 8 or more carbon atoms in the chain; by the inclusion of fatty acid glycerides, either raw or treated, such as raw or bodied linseed, China-Wood oil or the like. If desired, compatible natural'and synthetic resins such as, for

example, rosin, sandarac, copa-l, phenol-aldehyde,

urea-aldehyde, glycerin-phthalic anhydrid, vinyl and like resins, orcompatible cellulose derivatives such as, for example, high and low viscosity nitrocellulose, cellulose acetate, ethyl cellulose and like cellulose derivatives may be incorporated in the coating compositions in various proportions to meet any desired needs.

The choice and quantity of diluents, modifiers, plasticizers, and the like used in accordance with my invention is, of course, influenced by the purpose intended, the compatibility of the materials in the solutions and coating compositions, the specific properties desired in thecoating compositions and the films deposited therefrom as well as-by the known characteristics of the diluents, modifiers, plasticizers and the like utilized.

The fillers used in accordance with my invention may suitably be starch or fiber obtained from zein during the purification thereof, or some other suitable inert, fibrous, powdered materials such as cork, mica, sawdust, chalk, magnesite, clay, bentonite or equivalent colloidal clays, charcoal dust, pigments and the like. Any suitable color as well as opacity, where desired, may be imparted to the coating compositions, as by a pigment or dye, and the amounts of such coloring agents utilized may be varied rather widely to -meet any needs in paints, inks, ink bases and the like.

In the preparation of a printing ink or printing ink base, for example, a solution formed as above described is mixed directly with the desired pigments, including fillers'and coloring agent or mixtures thereof by any of the knownmethods such as by grinding in a stone paint mill, roller mill, ball mill or the like. If desired the pigments may be dispersed in a suitable-medium which is compatible with the zein vehicle, and the dispersed pigments may then be mixed with the ze'in like, or fatty acid glycerides, resin and oil and oil varnish compositions and the like which are compatible with the zein solution used. The proportions of pigments, coloring agent or agents to the vehicle may vary widely to produce inks of varying consistencies to meet any desired need. Thus, I have produced'suitable inks or ink bases wherein the pigment content varies from about 2% to about 85% by weight and the vehicle from about15% to about 98%. These inks may vary in consistency from a thick smooth paste to a thin, free flowing liquid.

The pigments and. coloring agent or agents utilized in printing inks in accordance with my invention may suitably be a black color such as, for example, carbon black, lamp black, animal or bone black and the like; a precipitated color such as for example, cadmium yellow, cadmium red, Prussian blue, ultramarine blue and the like; earth colors such as ochres, siennas, iron oxides and the like; white pigments such as white lead,

I zinc oxide, titanium oxide, lithopone and the like;

organic colors such as naphthol yellow S, Persian orange, lithol red, cosine, rhodamine, quino'line .yellow, indigo, methylviolet and the like; and

combinations of these coloring agents with fillers such as blanc flxe, barytes, asbestine, calcium carbonate, china clay, satin white and white pigments such as titanium oxide, lithopone, zinc oxide, white lead and the like.

It is, of course, obvious that the choice of the particular solution or vehicle combination utilized in preparing a printing ink in accordance with my invention is influenced by the properties desired in the ink and by the compatibility of the ingredients constituting the vehicle with the pigments and coloring agent .or agents. By a proper choice of the solvents for zein and of suitable modifying agents, the inks produced may be controlled as to consistency, drying time, flow, penetration, gloss, tendency toward thickening and action on the printing presses and the like. The choice of pigments and coloring agent or agents employed in accordance with my invention is likewise influenced by the properties desired in the inks as well as by the character of the vehicle wlthwhich it is to be mixed and the compatibility of the pigments and coloring, agents with the particular solution or vehicle used. The pigment and vehicle combinations should be of such character that undue thickening or livering does not take place.

What has been said hereinabove with specific reference to printing inks obviously applies, in general, to paints and like coatings.

- The following isan example of a printinglnk produced in accordance with my invention.

Example 45 containing not in excess of about 5% to form an ink having the consistency of a soft heavy paste.

While my invention has been described in connection with certain specific examples, it is, of course, obvious that my invention is not to be construed as limited to the specific materials disclosed in these examples or to the details of the methods set forth therein, since obvious changes in materials, proportions and method details will be apparent from the foregoing.

This application is also a continuation-in-part of my prior copending application Serial No.

187,559, filed January 28, 1938.

By the expression hydroxy organic solvent as used in the claims I refer not only to individual compounds which are solvents for zein but also to mixtures of compounds which may include 95% alcohol and which mixtures are solvents for zein. By the expression substantially anhydrous solvent as used in theclaims, I refer to individual solvents or to mixtures of solvents containing no added water, or only small amounts of added water in the order of about 1 to 3% and in no instance in excess of 5%.

I claim:

1. A substantially non-aqueous liquid coating composition comprising one part by weight of a 'prolamin and at least about 2' parts by weight of a substantially neutral, hydroxy organic solvent for the prolamin other than ethyl alcohol containing less than 5% of water, said composition of added water and-being stable against separation of the prolamin at temperatures of 70 F.

2. A substantially anhydrous liquid coating composition comprising one part by weight of zein and at least about 2 parts by weight of a substantially neutral, hydroxy organic solvent for water and being stable againstseparation of the zein at temperatures of 70 F.

4. A substantially non-aqueous liquid coating comprising one part by weightv oi zein andat least about 2 parts by weight of a solvent mixture containing less than 5%,of water comprising a substantially neutral, hydroxy organic solvent for the zein other than ethyl alcohol and a lacquer solvent other than the solvent for the zein, said composition containing not in excess of about 5% of added water and being stable against separation of the zein at temperatures of 70 F.

5. A substantially non-aqueous liquid coating composition comprising one part by weight of zein and at least about 2 parts by weight of a solvent mixture containing less than 5% of water comprising a substantially neutral, hydroxy organic solvent for thezein other than ethyl alcohol and a lacquer plasticizer, said composition containing not in excess of about 5% of added'water and being stable against separation of the fiin at temperatures of 70 F.

6. A substantially non-aqueous liquid coating composition comprising one part by weight of zein and at least about 2 parts by weightof a solvent mixture containing less 2 parts by weight of a.

- polar radicals of ethanol, I composition containing not in excess of 5% of solvent mixture containing less than-5% of water comprising a substantially neutral, hydroxy or ganic solvent forthe zein other than ethyl alcohol, a lacquer solvent other than the solvent for the zein and a lacquer plasticizer, said composition containing not in excess of about 5% of added water and being stable against separation of the zein at temperatures of 70 F.

'7. A substantially non-aqueous liquid coating composition comprising one part by weight of zein and at least about 2 parts by weight of a solvent mixture containing less than 5% of water comprising a major proportion of a substantially 2 neutral, hydroxy organic solvent for the zein other than ethyl alcohol and a minor proportion of a lacquer solvent other than the solvent for the zein, said composition containing not in excess ofabout 5% of added water and being stable against separation of atures of 70 F.

8. A substantially non-aqueous liquid coating composition'comprising one" part by weight ofv zein and at least about 2 parts by weight of a than 5% of water comprising a major proportion of a substantially neutrahhydroxy organic solvent for. the zein other than ethyl alcohol and a minor proportion of a lacquer plasticizer, said composition containing not in excess of about 5% of added water and being stable against separation of the zein at temperatures of 70 F.

9. A substantially non-aqueous liquid coating composition comprising one part by weight of zein and at least about 2 parts by weight of a solvent mixture containing less than 5% of water comprising a minor proportion of a substantially neutral, hydroxy organic solvent for the zein other than ethyl alcohol and a major proportion of a lacquer solvent other than the solvent for the zein, said composition containing not in excess of about 5% of added water-and being stable against separation of the zein at temperaturesvof 70 F.

10. A substantially non-aqueous coating composition comprising one part by weight oiE zein and at least about 2 parts by weight of a solvent mixture containing less than 5% of water the minor proportion of which is a substantially neutral, hydroxy organic solvent for the zein other than ethyl alcohol and the major proportion of which is a lacquer solvent other than the solvent for the zein and a lacquer plasticizer, said composition containing not in excess of about 5% of added water and being stable against separation'of the zein at temperatures of 70 F.

11. A substantially non-aqueous liquid coating composition comprising zein and a substantially anhydrous solvent for the zein having a proportion of polar to non-polar radicals which lies within a range extending between the limits of 60.

the proportion of polar to nSn-polar radicals of methanol and the proportion of polar to nonadded water, and said composition being stable against separation of the zein at temperatures of 70 F. and being relatively non-gelling. 12. A substantially non-aqueous liquid coating composition comprising zein anda substantially anhydrous solvent for the zeinlcomprisingt a mixture of organic compounds, said mixture of compounds having a proportion of polar to non-' polar radicals which lies within a range extendingbetweer'i the limits of the proportion of polar thezeinat tempersaid solvent and said to non-polar radicals of methanol and the-pro- I position being stable composition comprising a portion of polar to non-polar radicals of ethanol, said solvent and said composition containing not in excess of of added water, and said comagainst separation of thezein at temperatures of 70 'F. and being relatively non-gelling.

13. A substantially non-aqueous printing ink comprising a substantially non-aqueous vehicle comprising zein and a substantially anhydrous solvent for thezein having a proportion of polar to non-polar radicals which lies within a range extending between the limits of the proportion of polar to non-polar radicals of methanol and the proportion of polar to non-polar radicals of ethanol, said solvent and said composition containing not in excess of 5% of added water, and said composition being stable against separation of the zein at temperatures of 70 F., and being relatively non gelling. Y

14. A substantially non-aqueous printing ink comprising a substantially non-aqueous vehicle comprising zein and a substantially anhydrous solvent for the zein comprising a mixture of organic compounds, said compounds having a proportion of polar to non-polar radicals which lies within a range-extending between the limits of the proportion of polar to non-polar radicals of methanol and the proportion of polar to nonpolar radicals of ethanol, said solvent and said composition containing not in excess of 5% of added water, andsaid composition being stable against separation of the zein at temperaturesv F., and being relatively non-gelling.

A substantially non-aqueous liquid coating solution of zein in a substantially anhydrous mixture. of solvents having a proportion of polar to non-polar radicals which lies within a range extending between the limits of the proportion of polar to'non-polar radicals of methanol and the proportion of polar to non-polar radicals of ethanol, said mixture of solvents comprising an organic compound having a proportion of polar to non-polar radicals which lies within a range extending between the limits of the proportion ofpolar to non-polar radicals of methanol and the proportionof polar to non-polar radicals 01' ethanol and an alcohol of the class consisting of 95% alcohol and denatured ethyl alcohol, said composition containing not in excess of 5% of added water and being stable against separation of the zein at temperatures of 70 F. and being relatively non-gelling.

16. A substantially non-aqueous liquid coating composition comprising a solution of zein in a substantially anhydrous mixture of solvents having a proportion of polar to non-polar radicals which lies within a range extending between the limits of the proportion of polar to non-polar radicals of methanol and the proportion of polar to non-polar radicals ofethanol, said mixture of solvents comprising diethylene glycol and 95% alcohol, said composition containing not in excess of 5% of added water and being stable against separation of thezein at temperatures of 70 F., and being relatively non-gelling.

17. A substantially non-aqueous liquid coating composition comprising a solution of zein in a substantially anhydrous mixture of solvents having a proportion of polar to non-polar radicals which lies within a range extending between the limits of theproportion of polar to non-polar radicals of methanol and the proportion of polar to non-polar radicals of ethanol, said mixture of solvents comprising benzyl alcohol and 95% alcohol, said composition containing not in excess of 5% of added water and being stable against separation of the zein at temperatures of 70 F., and being relatively non-gelling.

18. A substantially non -aqueous liquid coating composition comprising a solution of zein in a substantially anhydrous mixture of solvents having a proportion of polar to non-polar radicals which lies within a range extendingbetween the limits of the proportion of polar to non-polar radicals of methanol and the proportion of polar to non-polar radicals of ethanol, said mixture of solvents comprising diacetone alcohol and 95% alcohol, said composition containing not inexcess of 5% of added water and being stable against separation of the 'zein at temperatures of 70 F., and being relatively non-gelling. 1 v

ROY E. COLEMAN. 

